| 摘要: |
| 【目的】对不同形态刨花压制麦秸板的主要物理力学性能进行比较和分析，为刨花原料的选择、板材制造工艺的改进提供理论指导。【方法】以聚合异氰酸酯为胶黏剂，采用不同加工方式（劈裂机加工和刨片机加工）及不同尺寸（经＞1～≤2 mm、＞2～≤4 mm、＞4～≤8 mm孔径筛分的3个等级的长料、短料）的麦秸刨花压制非定向的单层板材，根据林业行业推荐标准《LY/T 2141-2013定向结构麦秸板》的要求测试板材的物理力学性能，利用X射线断面密度测试仪分析刨花尺寸对麦秸板断面密度的影响。【结果】劈裂机加工的长料中，＞1～≤2 mm、＞2～≤4 mm、＞4～≤8 mm的麦秸刨花占75%左右，环式刨片机加工的短料中则为90%左右，刨片机加工的刨花中尺寸较小的刨花多于劈裂机加工刨花。长料的板坯压缩率为11.6，约为短料的1.3倍。随着筛孔孔径的增加，长料、短料的堆积密度减小，板坯厚度增加，压缩率也随之增加。在试验条件下，长料制得板材的抗弯强度与抗弯弹性模量分别为43.68 MPa和4.47 GPa，均约为短料的1.3倍，内结合强度为0.42 MPa，约为短料的74%；长料压制的麦秸板的24 h吸水厚度膨胀率和24 h吸水率分别为16.92%和60.64%，均高于短料，但后者差异不显著；长料板材的2 h吸水厚度膨胀率和2 h吸水率均高于短料板材，但差异均不显著。随着麦秸刨花长细比的增大，长料和短料中不同尺寸刨花压制麦秸板的抗弯强度与抗弯弹性模量均呈增大趋势，内结合强度均呈下降趋势，24 h吸水厚度膨胀率和24 h吸水率逐渐增大。不同尺寸麦秸刨花压制板材的密度均在厚度方向呈“面高芯低”式的“U”形分布。刨花尺寸对麦秸板断面密度的影响并不明显，可能是因为刨花尺寸相对较小，其影响相对较弱。【结论】长料各筛层刨花所压制的板材性能变化幅度较短料大。在实际生产中，建议将长刨花作为表层原料以提高板材的抗弯强度和抗弯弹性模量，将短刨花作为芯层原料以提高其内结合强度和尺寸稳定性。 |
| 关键词: 刨花形态 麦秸板 物理力学性能 |
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| 基金项目:西北农林科技大学基本科研业务费科技创新专项重点项目（QN2011071） |
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| Effect of particle geometry on physical and mechanical properties of wheat straw board |
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ZHENG Chao,ZHANG Ya-yun,XIAO Jian-ping,et al
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| Abstract: |
| 【Objective】This paper evaluated the effect of particle geometry on mechanical and physical properties of wheat straw board to improve practical production.【Method】Wheat straw boards were fabricated with two types of particles processed by splitter and flaker and three different diverse sizes (＞1－≤2 mm,＞2－≤4 mm,and ＞4－≤8 mm).Then the mechanical properties of panels were evaluated according to standard LY/T 2141-2013 and vertical profile density (VDP) was measured by X ray.【Result】Three different sizes of wheat straw particles with sizes of ＞1-≤2 mm,＞2-≤4 mm,and ＞4-≤8 mm accounted for about 75% and 90% of strands processed by splitter and flaker,respectively.Flaker processed more fine particles than splitter.The compression ratio of strands processed by splitter was 11.6,which was approximately 1.3 times of that processed by flaker.With the increase of mesh size,bulk density of raw materials decreased,while the thickness of mat and compression ratio increased.MOR and MOE of boards made of strands were 43.68 MPa and 4.47 GPa,respectively,which were 1.3 times of the boards made of particles.Besides,IB (0.42 MPa) was 74% of that made of particles,and 24 h TS and WA were 16.92% and 60.64%,all higher than the boards made of particles.2 h WA and TS were higher than the boards made of particles without significant difference.With the increase of slenderness ratio,the MOR and MOE increased,IB decreased,while 24 h TS and WA increased.VDPs were very similar for different boards made of different sizes of strands and particles with an approximate U-shaped distribution.It indicated that the influence of particle size on VDP was not significant.【Conclusion】Comparing with boards made of particles processed by flaker,strands processed by splitter had much larger variations in properties.In practical production, it is recommended to use strands as face material and particles as core material to improve the bending properties,IB and dimensional stability. |
| Key words: particle geometry wheat straw board physical and mechanical properties |
